Question: Tell me the astronomical observatory with the most observing time?
Paraphrase: Let me know the cosmic observatory with the foremost watching time?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q1254933 . ?ent wdt:P3891 ?obj } ORDER BY DESC(?obj)LIMIT 5 
Answer: Green Bank Observatory, Kitt Peak National Observatory, Xinglong Station, Shamakhi Astrophysical Observatory, Tartu Observatory